Procedure for regeneration of nickel baths



United States Patent 3,122,490 PRQCEDURE FQR PEGENERATlQN 0F NECKEL ATI-ltl Wennemar Strauss, Dnsseldorf-Holthausen, Germany, as-

signor to Belg dag Deutsche Hydrierwerke G.m.h. rl., Dusseldorf, Germany, a corporation of Germany No Drawing. Filed Mar. 26, 1962, Ser. N 132,674 Claims priority, application Germany June 12, 1961 it (Cl. 2:94-49 This invention relates to bright nickel electroplating baths which use heterocyclic nitrogen bases as a component of the bath. The invention more particularly relates to a method for the regeneration of such baths and to additives for eifecting such regeneration.

It is well known that derivatives of heterocyclic nitrogen bases such as pyridii e, quinoline, isoquinoline and the like are added to nickel baths to increase the brightening effect or to obtain a better leveling efiect. These derivatives are especially quaternary nitrogen bases which can be substituted at the heterocyclic ring and at the nitrogen. In the latter position saturated and unsaturated hydrocarbon radicals can be substituted, for example, alkyl, alkenyl and all-tinyl radicals. Suitable substituents for the same position are also mixed aliphatic-aromatic or aliphatic-cycloaliphatic radicals. As examples of such quaternary nitrogen compounds can be listed: N-alkylor N-alkenyl-pyridinium, -bis-pyridiniurn, -quinolinium, -isoquinolinium, -pyrazolpyridinium and pyrazolquiuolinium salts of hydrochloric acid, sulfuric acid and other organic or inorganic acids.

While these nickel baths are in operation, it often happens that the brightening and leveling efiects decrease and the baths finally are no longer able to maintain the same standard of efficiency. This decrease of the brightening effect is probably caused by the formation and concentration of by-products and decomposition products, especially free heterocyclic bases. This enrichment can be caused by th heterocyclic quaternary ammonium compounds which sometimes still contain remainders of free base or by the electrolytic decomposition products of these agents. In some cases it is possible to remove these heterocyclic bases or other troublesome products by treating the baths with active charcoal, but this method is not always successful.

The same disadvantage has also appeared in baths containing salt-like reaction products of tertiary monoor polycyclic heterocyclic nitrogen bases of the aromatic type and sultones which are special quaternary pyridiniurn, quinolinium or isoquinolinium compounds and the like of the sulfobetain type. The regeneration of the acidic nickel baths with active charcoal either is not possible at all or only to a very small extent.

it is therefore an object of this invention to provide a method for regenerating bright nickel electroplating baths containing heterocyclic nitrogen bases as additives.

A further object is to provide an additive compound for effecting regeneration of bright nickel electroplating baths containing heterocyclic nitrogen bases.

These and other objects of the invention will become apparent as the description thereof proceeds.

I have now found that the regeneration of these baths can be accomplished in a simple way by adding a small amount of a sultone, preferably LS-propane-sultone, to the bath while warming it. The addition can take place continuously or portionwise in certain intervals, for example, during the breaks. 0.13 g./l., preferably 0.5-1 g./l. are used. The regeneration takes place at elevated temperatures and has to be continued until all the byproducts and decomposition products are blocked by reaction with the sultone. The regeneration is accomplished at temperatures between 50100 C., technically preferkept at this temperature for fifteen minutes.

3,122,4h Patented Feb. 25, 1964 ice ably at 70-80 C. The duration of the regeneration action may be less the higher the temperature of the bath. The additive removes the disadvantageous effect of the impurities in a short time and returns the bath to its high elfective state. The reaction products of the impurities with the sultones may possibly have brightening effects. Addition of lactones to the bath leads to similar positive results, as with the sultones.

Not only 1,3-propanesultone can be used but also 1,4-butanesultone and their substitution products, such as tolylsultone, 1,8-naphthylsultone and the like. Useful lactones for the same purpose are, for example, 'y-butyrolactone and 'y-valerolactone.

The following specific examples are presented to illustrate the invention and to enable persons skilled in the art to better understand and practice the invention and are not intended to be lirnitative.

Example I A nickel bath of the Watts type containing pyridinlum- N-propane-w-sulfonic acid, as brightening and leveling agent showed a decrease in its brightening effect after having a current of 250 ampere hours per liter on the bath, which was reached after a working period of about two years. Usual methods of cleaning the cell by means of treatment with active charcoal or potassium permanganate were unsuccessful. 0.8 g./l. propanesultone were added to the bath and allowed to react for ten minutes at approximately C. After cooling down to 55 C., an additional 0.2 g./l. of the above-identified pyridinium compound was added and the bath again was put into operation. The nickel coatings again came out perfectly. Without treatment with propanesultone, the bath could not be regenerated either by heating to 90 C. for ten minutes or by adding 0.2 g./l. of pyridinium-N-propanew-sulfonic acid.

Example [I The nickel bath described in Example I was also regenerated by treatment with lactones. 0.6 g./l. 'y-butyrolactone was added to the bath which had decreased in its efficiency and the bath was heated up to -l(l0 C. and

After cooling down to 55 C., 0.2 g./l. pyridinium-N-propane-wsulfonic acid was added. Thereafter the bath was put into operation again with sufficient efliciency in respect to its brightening elfect. The nickel coverings came out in perfect condition.

Similar results were obtained with bright nickel baths when other pyridiniurn-N-alkane sulfonic acids were used as the brightening and leveling agents.

While I have set forth certain specific examples and preferred modes of practice of my invention, it will be understood that this is solely for the purpose of illustration and that various changes and modifications may be made without departing from the spirit of the disclosure and the scope of the appended claims.

I claim:

1. A process for regenerating a Watts type bright nickel electroplating bath containing heterocyclic nitrogen bases as brightening and leveling additive components which comprises, operating said bath under normal conditions unt l the effectiveness of the bath has fallen to a predetermined level of activity, adding a compound selected from the group consist ng of sultones and lactones to the bath in sufiicient amount to eifect said regeneration, and thereafter repeating said regeneration whenever said bath activity falls to said predetermined level.

2. A process for regenerating a Watts type bright nickel electroplating bath containing salt-like reaction products of tertiary monoand polycyclic heterocyclic nitrogen bases as brightening and leveling additive components which comprises, operating bath under normal conditions until the effectiveness of the bath has fallen to a predetermined level of activity, adding a compound selected from the group consisting of sultones and lactones to the bath in sufiicient amount to efiect said regeneration, and thereafter repeating said regeneration whenever said hath activity falls to said predetermined level.

3. A process for regenerating a Watts type bright nickel electroplating bath containing a pyridinium-N-alkane-wsulfonic acid as a brightening and leveling additive component which comprises, operating said bath under normal conditions until the elfectiveness of the bath has fallen to a predetermined level of activity, adding a compound selected from the group consisting of sultones and lactones to the bath in sufiicient amount to efi ect said regeneration, and thereafter repeating said regeneration whenever said bath activity falls to said predetermined level.

4. A process for regenerating a Watts type bright nickel electroplating bath containing heterocyclic nitrogen bases as brightening and leveling additive components which comprises, operating said bath under normal conditions until the effectiveness of the bath has fallen to a predetermined level of activity, adding the compound 1,3- propane sultone to the bath in suilicient amount to eifect said regeneration, and thereafter repeating said regeneration whenever said bath activity falls to said predetermined level.

5. A process for regenerating a Watts type bright nickel electroplating bath containing heterocyclic nitrogen bases as brightening and leveling additive components which comprises, operating said bath under normal conditions until the effectiveness of the bath has fallen to a predetermined level of activity, adding the compound butyrolactone to the bath in sufiicient amount to effect said regeneration, and thereafter repeating said regeneration whenever said bath activity falls to said predetermined level.

6. A process for regenerating a Watts type bright nickel electroplating bath containing heterocyclic nitrogen bases as brightening and leveling additive components which comprises, operating said bath under normal conditions until the effectiveness of the bath has fallen to a predetermined level of activity, adding from about 0.1 to 3 g./l. of a compound selected from the group consisting of sultones and lactones, and thereafter repeating said regeneration whenever said bath activity falls to said predetermined level.

comprises, operating said bath under normal conditions until the eifcctiveness of the bath has fallen to a predetermined level of activity, adding from about 0.5 to 1 g./l. of a compound selected from the group consisting of sultones and lactones, and thereafter repeating said regeneration Whenever said bath activity falls to said predetermined level.

8. A process for rege erating a Watts type bright nickel electroplating bath containing heterocyclic nitrogen bases as brightening and leveling additive components which comprises, operating said bath under normal conditions until the eifectiveness of the bath has fallen to a predetermined level of activity, adding a compound selected from the group consisting of sultones and lactones to the bath in sufficient amount to effect said regeneration, while submitting said bath to elevated temperatures, and thereafter repeating said regeneration whenever said bath activity falls to said predetermined level.

9. A process for regenerating a Watts type bright nickel electroplating bath containing heterocyclic nitrogen bases as brightening and leveling additive components which comprises, operating said bath under normal conditions until the effectiveness of the bath has fallen to a predetermined level of activity, adding a compound selected from the group consisting of sultones and lactones to the bath in sufiicient amount to effect said regeneration, while heating said bath to a temperature of from about to C., and thereafter repeating said regeneration Whenever said bath activity falls to said predetermined level.

10. A process for regenerating a Watts type bright nickel electroplating bath containing a pyridinium-N-alkane-wsulfonic acid as a brightening and leveling additive component which comprises, operating said bath under normal conditions until the effectiveness of the bath has fallen to a predetermined level of activity, adding from about 0.1 to 3 g./l. of a compound selected from the group consisting of sultones and lactones to the bath, while heating said bath to a temperature from about 50 to 100 (3., and thereafter repeating said regeneration Whenever said bath activity falls to said predetermined level.

References tilted in the file of this patent UNITED STATES PATENTS 2,876,177 Gundel et al. Mar. 3, 1959 

1. A PROCESS FOR REGENERATING A WATTS TYPE BRIGHT NICKEL ELECTROPLATING BATH CONTAINING HETERCYCLIC NITROGEN BASES AS BRIGHTENING AND LEVELING ADDITIVE COMPONENTS WHICH COMPRISES, OPERATING SAID BATH UNDER NORMAL CONDITIONS UNTIL THE EFFECTIVENESS OF THE BATH HAS FALLEN TO A PREDETERMINED LEVEL OF ACTIVITY, ADDING A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SULTONES AND LACTONES TO THE BATH IN SUFFICIENT AMOUNT TO EFFECT SAID REGENERATION, AND THEREAFTER REPEATING SAID REGENERATION WHENEVER SAID BATH ACTIVITY FALLS TO SAID PREDETERMINED LEVEL. 